It is known that particulate matter may be ground to a finer size by the use of a media mill which incorporates fine particles that, during stirring with an agitating device, reduce the size of the material to be ground. Such grinding devices have been shown in Japanese 46/6718--Tokai Kinzoku Kogyo Co., Ltd. and U.S. Pat. No. 4,303,205--Geiger et al.
Also known are devices such as in U.S. Pat. No. 3,998,938 which recirculate material through a media mill.
It is also known to use agitating means that have disks rather than arms in a media mill, such as disclosed in U.S. Pat. No. 3,601,322--Szegvari.